The present invention relates to an image processing apparatus which outputs pictures photographed as a digital moving image data. More to particularly, this invention relates to an image processing apparatus which is connected to an information processing apparatus such as a personal computer and so forth to be used.
1. Description of the Prior Art
There is a system in which a moving image can be handled in a television conference system using the information processing apparatus such as the personal computer and so forth. In such the system, a picture photographed by the camera is transferred to the information processing apparatus as, for instance, an image data in every frame unit. The information processing apparatus executes data compression processing to the image data to transfer the data to the distant place through LAN or communication channel. There is also a system for regenerating a picture which is photographed, by only a personal computer and so forth exception for the television conference system for transmitting-receiving an image data photographed through the image processing apparatus. In order to constitute such the system, it is necessary to transfer the photographed image to the information processing apparatus as a moving image data.
When the image data outputted from the image processing apparatus such as the camera and so forth is a digital data, such the digital image data, in many cases, is transferred to the personal computer and so forth by a universal interface. FIG. 1 is a system configuration view showing a system using USB (Universal Serial Bus) interface as a universal interface. The personal computer 10 is provided with two USB ports. In this example, a key board 11 is connected to one USB port. Further, several terminal equipments 20, 30, . . . 40 are connected to the USB through a USB hub 15 to which the other USB port is connected.
Here, supposing that the terminal equipment 20 is the camera as an image processing apparatus outputting a photographed image as a digital image data. When only the terminal equipment 20 is operated, the digital image data is transferred from the terminal equipment 20 to the personal computer 10 with stable frame rate because the terminal equipment 20 is capable of occupying the USB. However, when another terminal equipments 30, 40 are operating and the data is also transferred from another terminal equipments 30, 40 to the personal computer 10, transfer data from the terminal equipment 20 is transferred to the USB with time division operation. In such the case, a frame rate of the digital image data transferred from the terminal equipment 20 to the personal computer 10 deteriorates.
There is the problem that the conventional image processing apparatus is connected to the personal computer 10 as above method, therefore when the digital camera is used, another terminal equipments 30, 40 are incapable of being used synchronously. If the digital camera together with the terminal equipments 30, 40 are used synchronously, the frame rate of the image data from the digital camera deteriorates, thus frame omission occurs in the moving image data received by the personal computer 10.
In view of the foregoing, it is an object of the present invention, in order to overcome the above-mentioned problems, to provide an image processing apparatus which is capable of transferring image data with stable frame rate, and which causes no frame omission of moving image to occur, even though the apparatus causes another equipment to be operated synchronously on interface bus.
According to a first aspect of the present invention, in order to achieve the above mentioned object, there is provided an image processing apparatus which comprises a converting means reading an image of a subject to convert into an electric signal before outputting it, a quantizing means for outputting a quantized electric signal as an image signal while quantizing the electric signal outputted from the converting means, a transfer speed recognition means for detecting a transfer speed of the image signal outputted to an external part, a transfer data quantity converting means for converting data quantity of quantized the image signal from the quantizing means in accordance with the transfer speed detected by the transfer speed recognition means, and an interface means for outputting the image signal outputted from the transfer data quantity converting means.
According to a second aspect of the present invention, in the first aspect, there is provided an image processing apparatus, wherein the transfer speed recognition means detects the transfer speed of the image signal according to cycle of a transfer demand signal transmitted from a host apparatus which receives the image signal.
According to a third aspect of the present invention, in the second aspect, there is provided an image processing apparatus, wherein the transfer data quantity converting means is a quantization precision converting means for converting quantization precision of the quantized image signal from the quantization means, and the quantization precision conversion means, when the transfer speed recognition means detects that the cycle of the transfer demand signal is less than reference value, increasing quantization precision, while when the transfer speed recognition means detects that the cycle of the transfer demand signal exceeds the reference value, decreasing the quantization precision.
According to a fourth aspect of the present invention, in the third aspect, there is provided an image processing apparatus, wherein the quantization precision converting means outputs directly quantized image signal to the interface means in case where the cycle of the transfer demand signal is less than the minimum reference value of a plurality of reference values, while when the cycle of the transfer demand signal exceeds one reference value and the cycle is less than the other reference value, the quantization precision converting means reduces bit number of the quantized image signal in accordance with the other reference value to output to the interface means.
According to a fifth aspect of the present invention, in the fourth aspect, there is provided an image processing apparatus, wherein the quantization precision conversion means enables the bit number of the image signal which is changed in accordance with respective reference values to be altered.
According to a sixth aspect of the present invention, in the second aspect, there is provided an image processing apparatus, wherein the transfer data quantity conversion means is an information quantity conversion means for converting information quantity of the quantized image signal from the quantization means, and the information quantity conversion means, when the transfer speed recognition means detects that the cycle of the transfer demand signal is less than the reference value, increases information quantity, while when the transfer speed recognition means detects that the cycle of the transfer demand signal exceeds the reference value, the information quantity conversion means decreases information quantity.
According to a seventh aspect of the present invention, in the sixth aspect, there is provided an image processing apparatus, wherein the information quantity conversion means outputs directly a quantized image signal to the interface means in case where the cycle of the transfer demand signal is less than the minimum reference value of a plurality of reference values, while when the cycle of the transfer demand signal exceeds one reference value and the cycle is less than the other reference value, the information conversion means reduces the information quantity of the image signal in accordance with the other reference value to output to the interface means.
According to an eighth aspect of the present invention, in the sixth aspect or the seventh aspect, there is provided an image processing apparatus, wherein the information quantity conversion means is constituted such that it is capable of being changed the information quantity of the image signal changed in accordance with respective reference values.
According to a ninth aspect of the present invention, in any of the third, the fourth, sixth, or seventh aspects, there is provided an image processing apparatus, the transfer speed recognition means is constituted such that the reference value thereof is capable of being changed.
According to a tenth aspect of the present invention, in any of the first to the ninth aspects, there is provided an image processing apparatus, wherein the interface means is connected to USB.
The above and further objects and novel features of the invention will be more fully understood from the following detailed description when the same is read in connection with the accompanying drawings. It should be expressly understood, however, that the drawings are for purpose of illustration only and are not intended as a definition of the limits of the invention.